Police said a “multi-agency operation” had been launched due to the presence of “harmful chemicals”, but insisted there was no risk to the wider public.

They said the death was being treated as “non-suspicious”. It is believed the dead man was a 31-year-old from Dunfermline who went missing from his home on Thursday night. His family are understood to have contacted police after he was last seen in Leith, having crossed the Forth Road Bridge in a blue Ford Focus.

It is understood the “harmful chemicals” under investigation were found inside the man’s car.

Yesterday, a single bouquet of flowers had been left near the scene.

Stewartfield business owners said officers had been going from shop to shop asking for CCTV images from the night before. There was widespread confusion as a heavy police presence remained on site throughout the day, with a large segment of the industrial estate cordoned off.

A white forensics tent could be seen beside the Duke of Edinburgh’s Award Scheme store, but fences shielded most of the area from view.

Witnesses said police had told businesses to shut their doors and stay inside after the body was discovered on Tuesday night – before later asking them to evacuate.

Piano dealer Paul Crosbie described hearing sirens and said he was locked inside a shop unit for more than 20 minutes for “safety reasons”.

He reported seeing around a dozen officers donning protective “hazmat” suits as the area was cordoned off. Meanwhile, a spokesman for Taza Bake, a bakery specialising in Mediterranean wrap bread, said officers had told them to get off the site at around 10.30pm.

After requesting that they remained inside the bakery to finish production, workers were given a police escort off the estate at around 2.30am.

The spokesman said: “All that we heard was that someone has passed away inside a car. Police sealed off the whole area. They took all our details before we left.”

A police spokeswoman said the dead man’s family had asked for privacy to come to terms with their loss.

She said: “Police in Edinburgh were called to the Stewartfield area shortly after 7pm on Tuesday, March 1 following the discovery of a man’s body within a car.

“A multi-agency operation involving Police Scotland and Scottish Fire and Rescue Service resources took place due to concerns regarding the presence of harmful chemicals, but there is no risk to the wider public.”

Stewartfield Industrial Estate is home to 32 units and a wide variety of businesses, including gyms, bathroom fitters and a brewery.